Sensor with Interface for Functional Safety

ABSTRACT

A sensor interface operates to communicate a sensed quantity along one or more processing pathways and in different data representations. The signal representations can be swapped along one or more locations of the signal processing branches. These branches are independent from one another and combined at an interface component for transmission along a single path or node for a control unit.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application Ser.No. 61/847,097 filed Jul. 17, 2013, entitled “SENSOR DEVICE”, theentirety of which is incorporated herein by reference.

BACKGROUND

Functional safety represents a clear differentiator for current andfuture products in automotive industries. To achieve correspondingtargets in terms of automotive safety integrity level (ASIL) new andenhanced concepts have to be established. To achieve a dedicated ASILlevel different target parameters as failures in time (FIT) rate,diagnostic coverage, SPFM, LPFM, etc., have to achieve a dedicatedvalue.

For sensors, a typical safety goal is it to ensure dedicated signalaccuracy in a predefined time (e.g., 5° deviation of the true anglevalue has to be detected in 5 ms at an angle sensor). The problem to beovercome in that context is simply how to prove a dedicated diagnosticcoverage by specific safety mechanisms. The choice of safety mechanismsrepresents an important element and the more a dedicated mechanism isable to cover, the better.

An important element represents the interface between sensor and ECU, asthis can only be covered partly by internal checks as well as partly byexternal checks. Therefore innovative concepts for the interface areneeded, which cover the link between sensor and ECU in an optimal form.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a sensor interface system in accordancewith various aspects disclosed.

FIG. 2 is another block diagram of a sensor interface system inaccordance with various aspects disclosed.

FIG. 3 is another block diagram of a sensor interface system inaccordance with various aspects disclosed.

FIG. 4 is another block diagram of a sensor interface system inaccordance with various aspects disclosed.

FIG. 5 is a block diagram of a sensor interface system in accordancewith various aspects disclosed.

FIG. 6 is a waveform diagram of signals that can be transmitted fromsensors or sensor elements in accordance with various aspects disclosed.

FIGS. 7 a-7 b are waveform diagrams of signals that can be transmittedfrom sensors or sensor elements in accordance with various aspectsdisclosed.

FIGS. 8 a-8 b are waveform diagrams of signals that can be transmittedfrom sensors or sensor elements in accordance with various aspectsdisclosed.

FIG. 9 is a set of waveform diagrams of signals that can be transmittedfrom sensors or sensor elements in accordance with various aspectsdisclosed.

FIG. 10 is a block diagram of a sensor interface system in accordancewith various aspects disclosed.

FIG. 11 is a set of waveform diagrams of signals that can be transmittedfrom sensors or sensor elements in accordance with various aspectsdisclosed.

FIG. 12 is a process flow of a sensor interface system in accordancewith various aspects disclosed.

DETAILED DESCRIPTION

The present disclosure will now be described with reference to theattached drawing figures, wherein like reference numerals are used torefer to like elements throughout, and wherein the illustratedstructures and devices are not necessarily drawn to scale. As utilizedherein, terms “component,” “system,” “interface,” and the like areintended to refer to a computer-related entity, hardware, software(e.g., in execution), and/or firmware. For example, a component can be aprocessor, a process running on a processor, a controller, an object, anexecutable, a program, a storage device, and/or a computer with aprocessing device. By way of illustration, an application running on aserver and the server can also be a component. One or more componentscan reside within a process, and a component can be localized on onecomputer and/or distributed between two or more computers. A set ofelements or a set of other components can be described herein, in whichthe term “set” can be interpreted as “one or more.”

Further, these components can execute from various computer readablestorage media having various data structures stored thereon such as witha module, for example. The components can communicate via local and/orremote processes such as in accordance with a signal having one or moredata packets (e.g., data from one component interacting with anothercomponent in a local system, distributed system, and/or across anetwork, such as, the Internet, a local area network, a wide areanetwork, or similar network with other systems via the signal).

As another example, a component can be an apparatus with specificfunctionality provided by mechanical parts operated by electric orelectronic circuitry, in which the electric or electronic circuitry canbe operated by a software application or a firmware application executedby one or more processors. The one or more processors can be internal orexternal to the apparatus and can execute at least a part of thesoftware or firmware application. As yet another example, a componentcan be an apparatus that provides specific functionality throughelectronic components without mechanical parts; the electroniccomponents can include one or more processors therein to executesoftware and/or firmware that confer(s), at least in part, thefunctionality of the electronic components.

Use of the word exemplary is intended to present concepts in a concretefashion. As used in this application, the term “or” is intended to meanan inclusive “or” rather than an exclusive “or”. That is, unlessspecified otherwise, or clear from context, “X employs A or B” isintended to mean any of the natural inclusive permutations. That is, ifX employs A; X employs B; or X employs both A and B, then “X employs Aor B” is satisfied under any of the foregoing instances. In addition,the articles “a” and “an” as used in this application and the appendedclaims should generally be construed to mean “one or more” unlessspecified otherwise or clear from context to be directed to a singularform. Furthermore, to the extent that the terms “including”, “includes”,“having”, “has”, “with”, or variants thereof are used in either thedetailed description and the claims, such terms are intended to beinclusive in a manner similar to the term “comprising”.

In consideration of the above described deficiencies, various aspectsare directed towards sensor interface systems that transmit measurementdata of a physical quantity (e.g., a sensed quantity, a measuredquantity, a sensor signal, one or more signal components for a sensedsignal, or the like) via an interface without compromising data rate andinformation integrity. For example, one or more sensors can detect dataof a physical quantity with one or more sensor elements and communicatethe data in different representations via an interface to a controlunit, which, in turn, can control one or more sub-systems based on thedata received. Each sensor element can operate to alternate signalcomponents or data representations of the same sensed quantity togenerate a single signal output of the sensed quantity. For example,communication of measured data can be performed independently viaseparate signal pathways with the same physical quantity in differentrepresentations, which can be swapped (alternated, switched back andforth, sequenced, etc. among the data representations) from among signalpaths or within a single path to at a single output node as a sensorsignal. Components of the sensor interface system can operate to ensuredata integrity efficiently without compromising data rates by ensuringsignal accuracy in a predefined time period. A stuck at or error can bedetected by a controller (e.g., ECU) based on the different datarepresentations of a sensed quantity from a single sensor, for example.These two data representations can be transferred to an interface andany error in the data can be determined by a receiver component (e.g.,controller, ECU) according to the sequencing or separation of a range, atime domain, a multiplexing, or other representation that corresponds tothe different data representations, for example. Additional aspects anddetails of the disclosure are further described below with reference tofigures.

FIG. 1 illustrates a sensor interface system 100 that operates totransfer sensed data and information along processing paths and stagesin accordance with various aspects disclosed. The system 100, forexample, comprises a redundant or diverse sensing processing stage 102coupled to a signal processing stage 104 and an interface controlcomponent 106, which operate in conjunction to provide an output at asingle node or terminal 107 that is generated from different datarepresentations.

The interface system 100 can include a sensor that can comprise one ormore sensor elements 108, 110, in which each receive or generate asignal or signal component of a sensed measured quantity or property(e.g., a quantity of heat, pressure, magnetism, direction, orientation,etc.) for generating a single output signal of the sensed quantity atthe interface output. The sensor elements 108 and 110 can independentlyprovide signals or different signal components of an output signal 107to different sensor signal processing pathways 116 and 118 respectivelywithin the redundant or diverse sensing processing stage 102. Althoughtwo different paths 116, 118 are illustrated, interface architectureshaving only one path are also envisioned. The interface system cancomprise just on sensor element, in which various embodiments describedoperate along only one signal processing path with one signal processingcomponent 112 by alternating data representations of the same sensedquantity to provide a single signal of the sensed quantity at theinterface output. For example, the sensor elements 108 and 110 canoperate to communicate signal components respectively having differentdata representations, such as different trigonometric representations,inverse representations with respect to one another, different addendsof a sum, or other different proportional or inverse proportionalrepresentations with respect to one another.

For example, a polarity of a Hall sensor or other sensor can be swapped,alternated (back and forth), or sequenced in expressions, in which theentire signal pathway 116 and/or 118 can swap or alternate between twopoints. The different data representations can be altered within asingle signaling pathway from one or more sensor elements, or withindifferent signaling pathways from a plurality of sensor elements, toprovide a single signal output of the sensed quantity.

A “stuck at”, or a failure, in one component (e.g., signal processingcomponent 112 or 114) within the path 116, 118 or the branch 120, 122(including the interface 106) can be detected by an ECU or other controlunit receiving the output 107 comprising the different signal componentsbecause the differences in the data representations can be predeterminedand known to the ECU or other control. Thus, two different datarepresentations of a single signal of a detected or sensed quantity canbe communicated by an interface in a manner that the swapping of thedifferent data representations is visible to the receiving component(e.g., ECU or other control unit).

The different signal processing pathways 116 and 118 can comprise afirst sensing branch 120 and a second sensing branch 122 of the system100, which can be independent from one another and provide the samesensed quantity data in different representations from one another viaone sensor element in a branch (e.g., a magnetic field sensing sensor)providing different signal components in different representations ofthe same sensed quantity, or via more than one sensor element alongdifferent branches (e.g., an angle sensor comprising one or more sensorelements for providing a first angle value and one or more sensorelements for providing a second angle value). For example, the firstsensing branch 120 can be configured to provide a first sensor signalcomponent corresponding to the sensed quantity in a first representationof data, and the second sensing branch 122 can be configured to providea second sensor signal component corresponding to the sensed quantity ina different representation of the data. The different signals,communications or signal components from each sensor element 108, 110can then facilitate and form a single signal at a single node or output107 that is based on different data representations from each branch orwithin each branch 120, 122.

Each branch 120, 122 within the redundant or diverse sensing processingstage 102 can separately comprise a signal processing component 112 or114 that further processes data of the sensed quantity, which can beidentical in physical meaning, such as a same measurable or sensedquantity or value. The data from the branches 120, 122 can differ withrespect to one another in the representation that the data iscommunicated and be components of the same signal at the output 107. Forexample, the different data representations can be differenttrigonometric representations (e.g., cosine, sine) of the same measuredquantity, inversely proportional representations, proportionalrepresentations of the sensed quantity, sum components equaling one oranother quantity, or other representations of the sensed data orquantity that differ with respect to one another among the branches 120and 122. The different data representations can be generated atdifferent points along the interface system, such as before the signalprocessing components 112 or 114, after the components 112 or 114, orwithin the interface component 106, for example. For example, thedifference in representations can be the result of a separation of 0 to2¹¹⁻¹ for one representation or 2¹¹ to 2¹²⁻¹ for anotherrepresentations, in which the data representations can be differentwithin each single branch or pathway or swapped in representations fromamong the paths. Although different representations of data are swappedin polarity within one path or among different signaling paths, theinformation (e.g., sensed data, safety information, error code, or otherlike information) can still be discerned by the interface system foridentifying faulty data, maintain efficient processing rates, anderror-free processing for a control unit, which can further operatewithin a more complex system to facilitate accurate and function safetyof one or more sub-systems and is further detailed below.

The redundant or diverse sensing processing stage 102 is coupled to thesignal processing stage 104. The signal processing stage 104 comprisesat least a portion of the first processing pathway 116 and the secondsignal processing pathway 118, a first sensor processing component 112and a second sensor processing component 114. The first processingpathway 116 communicates an output of the first sensor element 108 to afirst sensor processing component 112, and the second processing pathway118 communicates an output of the second sensor element 110 to thesecond processing component 114. The first and second processingpathways 116, 118 can each comprise differential pathways, in which atleast two pathways are configured within each path for communicatingdata information and safety information along with correctional coding,such as one or more error correction coding, for example. The twodifferential signal paths of each pathway can be swapped from among oneanother in data representations so that the representations alter in apolarity, with respect to one another, or alternated between thepathways 116, 118, for example. Alternatively, the processing pathways116, 118 can each comprise a single link for communicating informationsuch as the same detected physical quantity (e.g., magnetic field,pressure, light, etc. in a unit of measure, signal value, direction,amplitude or the like) in different representations as signalscomponents for facilitating a single output signal 107 of a singlesensed quantity. The first signal processing component 112 can beconfigured to operate upon a first output of the first sensing branch120 and the second signal processing pathway 118 configured to operateupon a second output of the second sensing branch 122, in which eachsignal processing component can include one or more of normalizingcomponents, temperature calibration components, filters, calculatingcomponents (e.g., angle calculations or the like), analog-to-digitalcomponents (ADC), or control units comprising a processor or otherdevice components for processing and performing operations related toeach.

The system 100 includes an interface component 106 configured to providea modulated signal output that is a function of the first sensor signalcomponent or data representation and the second sensor signal componentor data representation to a node or a pathway 107 that provides the datato another control unit, processing device or other component, such asan ECU for further utilization. The interface component 106 is notlimited to any one interface type and can operate as a digital interfacecomponent configured for modulation and transfer of a digital bitstream, for example, or as a different interface such as a pulse widthmodulation interface component 106 for modulation or transfer of a pulsewidth modulated signal, in which further examples below detail more indepth.

Referring to FIG. 2, illustrated is another example sensor interfacesystem 200 that operates to transfer sensed data and information alongdifferent processing paths in different data representations forgenerating a sensor output signal in accordance with various aspectsdisclosed. The system 200 includes similar aspects discussed above, andfurther details the interface component 106, which comprises at leasttwo drivers and at least two transistors for generating high and lowperiods of a pulse width modulation (PWM) generation.

The interface component 106, as discussed above, operates as a singleinterface control unit for independent signal processing paths thatcommunicate a same measured sensed quantity simultaneously, at about thesame time, or concurrently and in different representations. Theinterface component 106 receives independent signals along theindependent processing pathways from the first signal processingcomponent 112 and the second signal processing component 114. Theinterface component 106 is not limited to any one type of interfacecontrol and can comprise a digital interface, PWM interface or othertype interface for communicating, modulating, or processing differentsignals from the two independent signal branches 120, 122. One exampleof the interface component 106 includes a PWM interface controlcomponent 106 that comprises a PWM high component 206, a PWM lowcomponent 208, a pull up transistor 210, and a pull down transistor 212.

The interfaces component 106 can operate by splitting the PWM operationinto independent hardware parts for the high and low period of the PWMgeneration within the interface component 106. The separation of thepath branches 120 and 122 of the system 200, for example, can be nearlyentire or almost complete, except for a single link or node 214 betweenboth branches, which can be also realized in a way that it can lead todetectable failures in case of single point faults or a “stuck at”(stuck at high, stuck at low, high ohmic output, wrong period, or thelike), if one or more components fail.

As discussed above, the two sensors elements (S1 and S2) 108 and 110 canoperate to deliver independent measurements of the same physicalproperty. For example, the different representations can have at leastone of opposite signs, different trigonometric representations, inverserelations, component portions of a sum, other proportional represents,or the like of the sensed quantity or property, and can be communicatedin different data representations such as via a separation in a dutycycle range, a time domain range, another range, or according todifferent time multiplexing so that the different data representationsenable a detection of an error. For example, the sensor elements can becomponents of a Hall sensor with opposite bias current directions, orsensor bridges (e.g., magnetoresistive (xMR) sensors or piezoresistors)with inverse setup, or the like. Furthermore, the sensing elements 108and 110 can be differently oriented with respect to the measuredmagnetic field or can be located in different spatial locations withknown differences of the magnetic field that is generated by theunderlying magnetic circuit. The signal processing SP1 and SP2components 112 and 114 can operate to calculate a calibrated outputsignal of each sensor measurement both covering a normalized signalrange 0 . . . 1. The signal processing can be performed in a way thatone output representation 202 of the branch 120 can be proportional tothe measured signal (x) and the other output 204 is following an inversefunction (1-x), in which other different data representations are alsoenvisioned as discussed herein with respect to the different branches120 and 122, for example. In the present figure, the sum of bothcomplementary signals could be predetermined to be one (within theaccuracy limits or a given tolerance of the measurements), or some othersum, which enables a receiving component or the ECU to determine whetherthere is a stuck at or error in the signally path of each branch.

One of the signal branches, for example, branch 120 can be assigned afirst control 206 that receives the output of the signal processingcomponent 104 and can be configured to operate an independent counter206. The first control 206 can operate to drive a high state of anoutput signal 107 such as a PWM signal or other output digital signal.The control 206 can drive the output driver 210 with Vdd 212, forexample, for a high state, as illustrated. Further, the other signalbranch, for example, branch 122 can be assigned a second or differentcontrol 208 that receives the output of the signal processing component114 and can be configured to utilize another counter 208, which isindependent from the branch 120 and corresponding components therein.The second control 210 can operate to utilize the independent counter asa driver for driving a low state of the output signal 107. The control208 can drive the output drive 210 to ground 216, for example, or tosome other low state. Although a PWM high and low is illustrated, thesignals can also be a simplified digital signal that is modulated from ahigh state 212 and a low state 216 such as a ground within the outputdriver 210 to generate the output at a path or node 107, such as a PWMoutput for example.

Referring to FIG. 3, illustrated is another aspect of the interfacesystems disclosed. The system 300 includes a single node 306 thatsupplies an output to one or more other control units, such as an ECU(not shown). The interface component 106 further includes a pull uptransistor 310 and a pull down transistor 312 that are operated by a PWMdriver circuit 302 and a PWM driver circuit 304 respectively. The PWMdriver 302 and PWM driver 304 are communicatively coupled to on anothervia a communication link 308, which can be for determining anoperational status, for example, among the drivers 302 and 304.

One of the signal branches, for example branch 120, can be assigned to ahigh state output PWM driver 302 of the interface component 106, whichcontrols a pull up transistor 310, and the other branch 122, forexample, can be assigned to the low phase or low state PWM output driver304, which controls a pull down transistor 312. The low state PWM driver304 can operate to test whether the high side transistor 310 isactivated, operational or actively conducting by injecting a testcurrent and measuring as voltage drop, which can be between Vdd 212 andground 216, for example. The driver 304 further operates to lock the lowside transistor 312 or the transistor gate control as long as the highside transistor 310 is conducting. Likewise, the high side driver 302can operate to monitor the low side transistor 312 conductivity in thesame manner and lock the high side gate driver or the controller 302 ifthe low side transistor 312 or the transistor switch is on, operationalor activated.

The resulting output can thus be a PWM output at the node 306 that isformed by two independent measurements, which each contribute to theduration of the high and low phase of the PWM independently. This canenable a simple checking of whether the two measurements correspond toone another or fit together, since the sum of both determine the PWMcarrier frequency, which should be independent of the signal. Forexample, if a failure occurs in the calculation of the signal processingbranch 120 or the signal processing branch 122, the sum of the valueswould not be equal to one anymore, which also means the period time ofthe signal will be changed and enables a detection of errors in thesignal processing. Thus, a direct recognition can be made from thereceived signal that there is a failure in the processing of the sensor.Other mechanisms for ensuring data accuracy and sensor interface controlare further detailed below. Furthermore, a failure of the driver stages,or the high side transistor 310 or low side transistor 312, will alsolead to an improper operation of the PWM output, which can be detectedwith a high probability if at least one of the following monitoringoperates is performed by the receiver of the PWM signal: a) monitoringof the logic high and low levels; and b) monitoring of the rise and falltime of the signal.

Referring to FIG. 4, illustrated is a sensor interface system 400 forinterfacing sensor data with a control unit in accordance with variousaspects disclosed. The system 400 includes similar components asdiscussed above, and further includes PWM controllers 402 and 404 thatoperate drivers or driver circuits 302 and 304 for pull up transistor310 and pull down transistor 312. The system 400 can further include aswitching component 403 with a sequence component 406 that alternatesthe signals or the signal paths along each branch 120 and 122 and withineach branch, from among differential paths of each branch, or from amongthe signal path branches 120, 122.

The switching component 403, for example, is configured to swap signalpaths or signal components from the sensor elements along the branches120 and 122. The switching component 406 can operate to swap signalspaths at various points or locations along the branches 120 and 122. Forexample, at location 410 the swapping can occur just after the outputsof the sensing elements 108 and 110. The signal outputs of each sensingelements can be swapped periodically so that each branch processes boththe signal of a first data representation X and 1-X, which can representa number of different data representations, as discussed above, otherthan ones that equal a sum of one, such as different trigonometricrepresentations (e.g., cosine, sine), inverse relations to one anotherwith respect to the different branches, or the other such datarepresentations of the same sensed quantity between the sensed elements108 and 110.

In another example, the signals paths or signals of the branches 120 and122 can be swapped in any number of sequences by the switching component406 and at other locations 412 or location 412 of the branch paths. Thelocation 412, for example, can include a location after any componentwithin the signal components 112 and 114, in which each can comprise anormalization component (not shown) for normalizing the signal along arange such as zero and one, a temperature calibration component (notshown) for calibrating for temperature variables, analog-to-digitalcomponents (ADC), or control units comprising a processor or otherdevice components for processing and performing operations related toeach.

Alternatively or additionally, the switching component 403 can swapsignal paths of signal components of one branch with the other withinthe interface 106, such as after the PWM controller PWM 1 402 and PWM 2404, for example. The PWM controller 402 and PWM controller 404 canoperate to perform pulse width modulation and generate pulse widthmodulated signals at teach output. The PWM controllers 402 and 404 canalso operate to test the drivers 302 and 304 based on monitoringsignals. The PWM controller 402 can operate to inject a test current andmeasure a voltage drop of the low side transistor 312, and then lock thehigh side driver 302 if the low side transistor is conducting. Further,the PWM 2 controller 404 can operate to also determine whether the highside transistor 310 is conducting and lock the low side driver or gate304 during operation of the pull up transistor 310 based on thedetermination. The high state driver or component 302 can be configuredto receive the first output from the first signal processing path andcontrol the pull up transistor 310 and the low state driver or component304 configured to receive the second output from the second signalprocessing path and control the pull down transistor 312. The durationof an operational status of the pull up transistor 310 or of the pulldown transistor 312 can be based on a range of separation along a signalrange of the first sensor signal and the second sensor signal, or a timeof separation in a time domain of the first sensor signal or signalcomponent and the second sensor signal or signal component.

The switching component 403 is configured to swap the first sensorsignal component received for processing at the first sensing branch 120with the second sensor signal component received for processing at thesecond sensing branch 122 at any one of locations 410, 412, or 414, forexample. Alternatively or additionally, the switching component 403 canoperate to switch polarities of the signal components of the switchingelements 108 and 110. The switching component 403 can further include asequence controller component 406 that is configured to control theswitching component 403 based on the monitoring signals that determinean operational status of a pull up transistor and a pull downtransistor. As discussed above, the monitoring of the signals or signalcomponents can be controlled by the PWM controllers 402 and 404.Alternatively the driver circuits 302 and 304 could be configured togenerate test or monitoring signals that are also communicated to theswitching component 406.

In one aspect, the sequence component 406 can initiate switching of thesignal paths from one branch to the other, or among each branch, so thateach switching path processes signals or the signal components from eachsensor element or sensor bridge (e.g., a bridge circuit or the like) ofthe one or more different representations (e.g., X, 1-X, cosine, sine,or the like). The sequences can be done in different manners orpolarities. For example, a polarity switching among or within thebranches can be performed by the switching component 403 in anasymmetrical sequence like ++-++-++- in this case the two identicalperiods can be identified by the ECU that receives the PWM modulatedsignal (not shown) as the one with regular polarity and the singledifferent period as the inverse one.

Further, the switching component 403, such as via the sequence component406, can be configured to alter the carrier frequency for the differentpolarities like long+short-long+short-. In this case the duration of thesum of high and low phase can mark the polarity or differences betweenthe data representations. Additionally or alternatively, a marker can beinserted at a known point in the polarity switching sequence likem+-m+-m+- (e.g. a short high low sequence which does not fall into theregular range of the PWM operation).

In one aspect, recognition of the different data representations X or1-X can be performed by an ECU 420 that receives the PWM signalaccording to different mechanisms, such as via different duty cycles orrange of separations within duty cycles. For example, identifying whichsignal received could be X or 1-X, or in the case of an angle sensorinterface, cosine or sine, an inverse relationships or the otherdiffering representations enables distinguishing between the signals ofbranch 120 and branch 122. In one aspect, the duty cycles of the signalscould be altered to recognize the different data representations fromthe signal path branches. For example, one duty cycle can be a multipleof another and correspond to the branch 122 for signal 1-X, and theother duty cycle can be identified as a factor of the first, or oppositedata representation, X and as corresponding to signal branch 120, forexample. This can operate in situations, for example, where samplingfrequencies are high and X is not changing much, or the period is notchanging drastically. In another aspect, a separation of the signalrange within a duty cycle and a time frame or signal period can alsoenable identification of the different signal representations. Further,the differences in representation can be distinguished by a separatingin the time domain where switching between the two representations orsignal paths can be performed continuous and utilize an entire PWMrange, in which a synchronization components operates to synchronize thetime periods for the signals. Even though the signal itself is the same,the different representations can enable the detection of errors at theinterface. An ECU is then able to also recognize how to interpret thedifferent representations to a real or functional value. The ECU orother control unit can be configured to detect an error of the sensorstage, the signal processing stage or the interface based on a detectionof the first data representation or the second data representation notcorresponding to the difference or separation in a range (e.g., a dutycycle range, time range, frequency range or the other range ofdifference), a time domain difference or separation, or a different intime multiplexing, for example.

In another aspect, an internally monitoring can occur for each dutycycle such as with a watchdog component or a synchronizing component408. The synchronizing component 408 can be configured to determinetimeframes associated with the first signal component and the secondsignal component, in which the first data representation and the seconddata representation different with respect to one another based ondifferent time multiplexing or other differences in representationsdiscussed herein. The synchronizing component 408 can operate a watchdogfunction by internally comparing the PWM period with an independentoscillator coupled thereat. The synchronizing component 408 can beconfigured to generate a comparison of a signal period with anindependent oscillator and synchronize or reset a period of the firstsensor element 108 that generates a first sensor signal, or of thesecond sensor element 110 that generates the second sensor signal, basedon the comparison.

Referring now to FIG. 5, illustrated is another example of a sensorinterface system in accordance with various aspects described. Thesensor elements 108, 110, for example, can comprise magnetic sensorelements or bridge circuit components of a sensor (e.g., an anglesensor, vertical Hall sensors, anisotropic magnetoresistance (AMR)sensor giant magnetoresistance (GMR), tunnel magnetoresistance (TMR), orthe like) that operate to detect a physical quantity of a magneticfield. For example, the sensor element 108 can comprise a co-sinusoidalcomponent 108 and a sinusoidal component 110, which can reside on asingle die or processing chip area to integrate the sensing elements onan integrated circuit.

The sensing elements 108 and 110 can operate to generate differentialoutputs for X and Y components of a rotating magnetic field. The outputscan be differential analog outputs, for example, that are furtherprovided to the signal processing components 112 and 114 respectively inindependent processing paths and can comprise different signals from thesame sensor, different sensor signals from different sensors, ordifferent signal components (different polarities) in different datarepresentations of the same measured quantity (e.g., a same magneticfield quantity) to generate a single signal of a single sensed quantityfrom different representations. The sensing elements 108 and 110, forexample, can comprise four or more AMR elements that sense anX-component, a Vx component (cosine), and the Y-component, and Vy (sine)of a magnetic field, such that a direction and a magnitude can becommunicated with a cosine function and a sine function respectively.The processing branch 120, for example, can comprise a cosine quantityand the processing branch 122 can comprise sine quantity of the samesensed quantity, in which each branch can comprise a differential signalbranch for providing sensor data and safety information corresponding toeach of the X values (X component and cosine) and the Y values (ycomponent and sine) as different signals components for a single sensorsignal of a sensed value or quantity, for example.

The signal processing components 112 and 114, as discussed above cancomprise various signal processing components along an independentsignal processing path or pipeline that is independent from one anotherwithin respective processing branches 120 and 122, such that noconnections are fixed among the paths and processing along eachcomponent is independent from components of the other processing branch.In one aspect, the only permanent physical connection, for example, canbe seen at the node 306 for providing an output signal from theinterface system 500 that is a function of the different datarepresentations. Each signal processing component 112, 114 can includeone or more of normalizing components for normalizing a range (e.g.,zero to one), temperature calibration components, filters, calculatingcomponents (e.g., Cordic, angle calculations or the like),analog-to-digital components (ADC), or control units comprising aprocessor or other device components for processing and performingoperations related to each.

Each of the branches 120 and 122 further comprise an angle component 502that can determine an angle derived from outputs of the signalprocessing components 112 and 114. The angle component 502 comprises anarctan component 504 and an arctan component 506 that respectivelyoperate to determine an angle as a function of the respective signalsreceived. Although arctan component 504 is illustrated as arctan y/x andarctan component 506 is illustrated as arctan x/y, each component canfunction as either or both for determining angle calculations. Each ofthe arctan components 504, 506 can be independent from one another andthe outputs can be processed as a sum that equals one or a differentvalue for recognizing as either branch 120 or 122, or as originatingfrom sensor element 108 or 110, for example. Alternatively, other meansof recognizing the signal origins can also be utilized, as discussedabove and further detailed below.

The switching component 403 can be configured to switch the sine andcosine signals along a signal processing branch, or switch between ameasured value and a reference value of the sensors. The switchingcomponent 403 can also include the sequencing and synchronizingcomponents for switching signal paths between the first processingbranch 120 and the second processing branch 122 according to one or moresequences. The sequence of switching can be a function of a watchdog oroscillator (e.g., synchronizing component 408) component that determinesa reset of a period and monitors period tolerances, for example. Theswitching component 403 can swap the signals from the differentprocessing branches from the first branch 120 to the second branch 122,or vice versa, at different locations, such as before the sensorprocessing components 112 or 114, along a point within multiplecomponents of the sensor processing components 112 and 114 therein,before the angle component 502, or after the angle component 502 andbefore the interface control component 106 for PWM output generation ata node or output path.

Referring to FIG. 6, illustrated is a graph representation of thedifferent signals. For example, the plot 600 represents an example ofsignals at a point in the processing branch 120 and in the processingbranch 122. The x-axis represents angles in degrees, and the y-axisrepresents the arctangent of each signal path as computed by the anglecomponent 502. The dotted line represents the signal computationcorresponding to the processing branch 120 and the dashed linerepresents the signal computation corresponding to the processing branch122. The solid line represents the sum of the two calculations, or ofboth sensor elements, in which the output of X and 1-X is processedtogether as a sum and can be used to determine whether an error hasoccurred.

In one aspect, the different signals can be different representations,such as inverse representations, or other different representations,which can be proportional, linear or other representation of the samesensed physical quantity. By switching the signals via the switchingcomponent 403 the entire signal path is followed in a correct way, suchthat if the predefined values are not achieved, an error can beidentified, such as the detection of a stuck at. The predefinedswitching between values can fully comprise the sensed information, suchas the case when switching between a sine signal component or a cosinesignal component of an angle sensor, which can be a sine or cosinequantity of the same measured quantity from the sensor elements orsensor bridge components.

In another aspect, the interface protocol can be defined differently sothat the interface system, such as via the interface component 212 isoperable to indicate an origin of the difference from among thedifferent representations. For example, indicating the origin ofdifference between the signals of the different signal processingbranches 120 and 122 can be performed via a separation of the signalrange. A PWM signal can be separated within a range of a duty cycle, forexample, such that a first half of a range of the duty cycle provides arepresentation of one signal along from a first sensor element andanother or second half of a range of the duty cycle can correspond tothe second data representation. Alternatively or additionally, an originof the difference can be recognized via a separation of a frequencydomain or of a time domain, in which the switching component 403 canswitch continuously among the two different data representationsutilizing an entire or whole PWM range. In the latter case, asynchronization component of the switching component 403 can be utilizedfor ensuring the proper time frame is recognized.

Referring to FIG. 7 a, illustrated is a set of signal representationsfor a sensed quantity that are plotted for a timeframe with a value(e.g., quantity, measure, magnitude, or like value) that is representedalong the x-axis and a duty cycle percentage along the y-axis. A sensedquantity that is detect by each sensor element 108, 110 can berepresented by the plot 702. The same value/signal value is transferredin a different representation and a range is split into two areas orportions of a range of separation for a duty cycle over a time frame.Therefore, the plot 704 illustrates one data representation of a sensedquantity and the plot 706 illustrates another data representation of thesame sensed quantity, in which each plot 704 and 706 provides adifferent range of the signal along the duty cycle to distinguish thesame sensed quantity provides by different signaling paths or branchesalong the interface from different sensor elements. This enables theinterface to distinguish between a crossed mode (e.g., in a case wheresignal components of a different data representation of a differentsensor element is swapped) or a normal mode (e.g., in a case where asignal component generated from a sensor element of the correspondingbranch) in order to determine which sensor element or signal branch ofthe interface the signal being received originates from. For example,the value 50 could be delivered with 25% of the duty cycle range at onetimeframe and 75% at the other timeframe so that the value, or sensedquantity, is the same. Each data representation is unique or differentfrom among the two sensor elements 108, 110, and is able to beidentified at the ECU or other control unit.

For example, an angle sensor could have the sensor elements 108 and 110discussed above that have provided sensed data in differentrepresentations with respect to each other so that sensor element 108always communicates a sine value and the sensor element 110 alwayscommunicates a cosine value for determining a resulting angle, forexample. As the signal components from each sensor element are switched(e.g., a polarity is changed within the sensor elements 108, 110), aresulting angle can be different and is transferred by at least one ofthe different representation discussed herein.

Referring to FIG. 7 b, illustrated is a pulse train of the signals alongat least one branch of a sensor interface system in accord with variousaspects disclosed. The pulse train 710 demonstrates two different datarepresentations of signals that can be received along at least onesignal branch of the interfaces systems discussed, in which switching ofthe branch signals is conducted via a switching component 403, forexample. The data is represented according to a separation in a timedomain, in which the PWM signal of one data representation is separatedin time compared to another data representation and corresponding valuesdiffer according to the separation. For example, a value of 50 could berepresented at 25% duty cycle of the time in time frame one and 75% dutycycle at time frame 2. In response to the interface component or anothercomponent of the interface system receiving the different datarepresentations corresponding to the different timeframes, the interfacecomponent can operate to calculate back to the original value based onthe predetermined separation in the time domain. Other differentrepresentations are also envisioned and the representations are notlimited to any one particular example discussed herein.

Referring to FIG. 8 a, illustrated is a set of signal plots 800 thatillustrate different representations of signals provide by differentsensor elements detecting the same sensed quantity. In another aspect, asame value or sensed quantity shown in the plot 802 can be transferredvia different representations within the same range as shown by plots804 and 806, but are time multiplexed such that signals appeardifferently on the duty cycle in different fractions of the time periodor time frame in a sequence (e.g., an alternating sequence), forexample. In one example, a value of 25 represented by the circle alongthe plot of the sensed quantity can represent 25% duty cycle at one timeframe (e.g., Timeframe 1) in the plot 804, and 75% duty cycle at asecond time frame (e.g., Timeframe 2). The representation is not uniqueas such and thus the timeframes can be distinguished from one another asa function of the synchronization or synchronizing component 408 forexample.

FIG. 8 b illustrates a pulse train 810 that demonstrates thesynchronization 812 via the synchronizing component 408, for example.The signal range can also be restricted to comprise 5% to 95%, or someother different range, such that the signal outside of the range can beused for synchronization for determining which period or time frame(e.g., Timeframe 1 or Timeframe 2) is being received and determining theorigin of the signal. After synchronizing 812, the interface receivingcomponent can operate to identify the data. Switching between tworepresentations is based on crossing or inverting sine or cosine in thesensor bridges defining the sensor elements on a same die area of aprocessing chip, for example.

Referring now to FIG. 9, illustrated is a set of plots 900 illustratingtransfer functions and PWM data being sent of the calculated angle. Toensure that none of the signal path branches have a stuck at or afailure occurring in the processing operations of each branch of theinterface system, the signal paths can be crossed or inverted in theplots. This leads to a different transfer function of the calculatedangle as indicated by the angle transfer function plot 902 of themeasured angle versus the mechanical angle. The plot 904 represents thetransfer function of the sent PWM data of the duty cycle versus themechanical angle or reference angle among the two different datarepresentations combined, and the plot 906 represents the sent PWM datacombined with a guard band or narrowing region of the duty cycle forfurther transferring status information and/or synchronizing. Theadditional guard band region can enable the signals to communicate errorcoding and further data for determining error in the signal transmissionby communicating in a duty cycle range or other range that is less thanan entire range.

Referring to FIG. 10, illustrated is a sensor interface systemcomprising the signal processing branches according to aspectsdisclosed. The sensor interface system 1000 includes differential signalpaths along each processing branch 120, 122. The switching component(not shown) can operate to invert the values of each path with respectto the other within each processing branch 120 or 122, for example. Inan aspect, the signals of branch 120 can be inverted with respect to thesignal of the branch 122. In another aspect, the signals of each signalprocessing path or branch 120 of a corresponding sensor element 108, forexample, can be switched or swapped in sequences within the path branch120. Likewise, the signal processing branch 122 can be switched betweenthe differential paths of the branch 122. In one example, the signals ofeach branch can be inverted, either within differential processing pathsof each branch 120 with different polarities, 122 or from among thedifferent branches 120, 122, as discussed above.

Referring to FIG. 11, is illustrated is a set of plots 1100 illustratingtransfer functions and PWM data being communicated of the calculatedangles with inverted sine and cosine signals. To ensure that none of thesignal path branches have a stuck at or a failure occurring in theprocessing operations of one or more components of each branch in theinterface system, the signal paths can be crossed or inverted in theplots. This leads to a different transfer function of the calculatedangle as indicated by the angle transfer function plot 1102 of themeasured angle versus the mechanical angle. The plot 1104 represents thetransfer function of the PWM data of the duty cycle versus themechanical or reference angle among the two different datarepresentations combined. The plot 1106 represents the sent PWM datacombined with a guard band or narrowing region of the duty cycle forfurther transferring status information and/or synchronizing. The twodifferent representations are still unique and enable the control unit(e.g., ECU) or other receiving component to calculate the mechanicalangle.

While the methods described within this disclosure are illustrated inand described herein as a series of acts or events, it will beappreciated that the illustrated ordering of such acts or events are notto be interpreted in a limiting sense. For example, some acts may occurin different orders and/or concurrently with other acts or events apartfrom those illustrated and/or described herein. In addition, not allillustrated acts may be required to implement one or more aspects orembodiments of the description herein. Further, one or more of the actsdepicted herein may be carried out in one or more separate acts and/orphases.

Referring to FIG. 12, illustrated is a method 1200 for sensor interfacesystems in accordance with aspects disclosed. The method 1200 initiatesat 1202 and comprises providing a first signal component or first datarepresentation of a sensed quantity from a first sensing element (e.g.,108) to a first signal processing path (e.g., signal processing branch120).

At 1204, the method comprises providing a second signal component orsecond data representation of the same sensed quantity from a secondsensing element in a different representation within the first signalprocessing path or to a second signal processing path (e.g., branch122), which can be concurrent to, simultaneously or at about the same asact 1202.

At 1206, an output signal (e.g., a PWM or digital interface outputsignal) is generated at a node as a function of or based on a firstsignal and a second signal, or the first signal component or datarepresentation and the second signal component or data representation.

The method 1200 can further comprise switching or alternating the firstsignal component or data representation of the sensed quantity to thesecond signal component or data representation based on a switchingsequence. The different signal components or data representations can befrom different paths or within each path, in which the first signalprocessing path or branch and the second signal processing path orbranch can be different in representation as a sine signal or a cosinesignal, for example, or as an inverted signal with respect to oneanother. The signals can be represented differently, for example, by aseparation in a range, such as a range of a duty cycle so that theorigin (the first sensor element or the second sensor element) of eachsignal is able to be distinguished via different ranges in the signal.For example, each signal from among the two sensor elements can comprisea different percentage of a duty cycle. Alternatively or additionally,the separation can occur in a frequency domain or in a time domain. Thesignals can also be time multiplexed and the time periods identified bya synchronizing component having an oscillator, for example.

The method 1200 can further comprise providing a test signal to a pullup transistor of an interface component that is coupled to the firstsignal processing path, and providing a test signal to a pull downtransistor coupled to the second signal processing path to determine anoperational status of the pull up transistor and the pull downtransistor. In response to determining the operational status, the firstsignal of the sensed quantity can be switched or swapped with the secondsignal processing path and the second signal of the sensed quantityswitched with the first signal processing path.

Although the disclosure has been shown and described with respect to oneor more implementations, equivalent alterations and modifications willoccur to others skilled in the art based upon a reading andunderstanding of this specification and the annexed drawings. Further,it will be appreciated that identifiers such as “first” and “second” donot imply any type of ordering or placement with respect to otherelements; but rather “first” and “second” and other similar identifiersare just generic identifiers. In addition, it will be appreciated thatthe term “coupled” includes direct and indirect coupling. The disclosureincludes all such modifications and alterations and is limited only bythe scope of the following claims. In particular regard to the variousfunctions performed by the above described components (e.g., elementsand/or resources), the terms used to describe such components areintended to correspond, unless otherwise indicated, to any componentwhich performs the specified function of the described component (e.g.,that is functionally equivalent), even though not structurallyequivalent to the disclosed structure which performs the function in theherein illustrated exemplary implementations of the disclosure. Inaddition, while a particular feature of the disclosure may have beendisclosed with respect to only one of several implementations, suchfeature may be combined with one or more other features of the otherimplementations as may be desired and advantageous for any given orparticular application. In addition, the articles “a” and “an” as usedin this application and the appended claims are to be construed to mean“one or more”.

Furthermore, to the extent that the terms “includes”, “having”, “has”,“with”, or variants thereof are used in either the detailed descriptionor the claims, such terms are intended to be inclusive in a mannersimilar to the term “comprising.”

What is claimed is:
 1. A sensor system comprising: a sensor stagecomprising at least one sensor element of a sensor configured to providea first signal component in a first data representation and a secondsignal component in a second data representation to generate a sensorsignal of a sensed quantity in different representations; a signalprocessing stage, coupled to the sensor stage, comprising a first signalprocessing branch configured to operate upon the first signal componentof the first sensor element and the second signal component of thesecond sensor element; and an interface configured to provide the sensorsignal as a function of the first signal component and the second signalcomponent to a node.
 2. The sensor system of claim 1, wherein the firstsignal component and the second signal component comprise a proportionalrelationship to one another and differ according to differentrepresentations of the sensed quantity that comprise differenttrigonometric representations or different inverse representations ofthe sensed quantity.
 3. The sensor system of claim 1, furthercomprising: a control unit component configured to detect an error ofthe sensor stage, the signal processing stage or the interface based ona detection of the first data representation or the second datarepresentation not corresponding to a separation in a range or aseparation in a time domain.
 4. The sensor system of claim 1, furthercomprising: a switching component configured to alternate the firstsignal component received for processing at a first sensing branch withthe second signal component received for processing at a second sensingbranch, or alternate a polarity of the first signal component at thefirst sensing branch.
 5. The sensor system of claim 4, furthercomprising: a sequence controller configured to control the switchingcomponent based on a set of monitoring signals configured to determinean operational status of a pull up transistor and a pull downtransistor.
 6. The sensor system of claim 1, further comprising: asynchronizing component configured to determine timeframes associatedwith the first signal component and the second signal component, whereinthe first data representation and the second data representation differwith respect to one another based on different time multiplexing.
 7. Thesensor system of claim 6, wherein the synchronizing component is furtherconfigured to generate a comparison of a modulated signal period with anindependent oscillator and synchronize the at least one sensor elementbased on the comparison.
 8. The sensor system of claim 1, furthercomprising: a high state component configured to receive a first outputfrom the first signal processing path of a first sensor element andcontrol a pull up transistor; and a low state component configured toreceive a second output from a second signal processing path coupled toa second sensor element and control a pull down transistor, wherein aduration of an operational status of the pull up transistor and of thepull down transistor is based on a range of separation along a signalrange of the first signal component and the second signal component, ora time of separation in a time domain of the first signal component andthe second signal component.
 9. The sensor system of claim 8, furthercomprising: a low side controller configured to lock the low statecomponent based on a determination of whether the high state componentis actively operating the pull up transistor; and a high side controllerconfigured to lock the high state component based on a determination ofwhether the low state component is actively operating the pull downtransistor.
 10. The sensor system of claim 1, further comprising: aswitching component configured to alternate the first signal componentin the first data representation of the sensed quantity from the firstsensor element with the second signal component in the second datarepresentation of the same sensed quantity within the first signalprocessing branch and a second signal processing branch, wherein thefirst data representation and the second data representation differbased on a separation of a range of a duty cycle.
 11. A sensor interfacemodule for interfacing one or more sensor signals between at least onesensor and an engine control unit comprising: a first sensor elementconfigured to communicate a measured quantity in a first datarepresentation; a second sensor element configured to communicate themeasured quantity in a second data representation; a switching componentconfigured to swap between communicating the first data representationof the measured quantity and the second data representation of themeasured quantity; and an interface component configured to generate anoutput signal to a node as a function of the first data representationand the second data representation.
 12. The sensor interface module ofclaim 11, wherein the engine control unit is configured to receive theoutput signal at the node and interpret the output signal based on thefirst data representation and the second data representation differingfrom one another as a function of a separation in at least one of a dutycycle range, a time domain range, or a time multiplexing.
 13. The sensorinterface module of claim 11, wherein the first data representationcomprises at least one of a first addend of a sum and the second datarepresentation comprises a second addend of the sum, a cosinerepresentation and a sine representation, or a first inverserepresentation and a second inverse representation, respectively. 14.The sensor interface module of claim 11, further comprising: asynchronizing component configured to generate a comparison of amodulated signal period of the output signal with an independentoscillator, wherein the first data representation and the second datarepresentation differ based on a time of separation in a time domain.15. The sensor interface module of claim 11, wherein the first sensorelement comprises a first sensor bridge configured to generate the firstdata representation of the measured quantity, and the second sensorelement comprises a second sensor bridge configured to generate thesecond data representation to comprise a proportional relationship toone another and differ according to different representations of themeasured quantity that comprise different trigonometric representationsor different inverse representations of the measured quantity.
 16. Thesensor interface module of claim 11, wherein the switching component isfurther configured to swap a first signal component in the first datarepresentation and a second signal component in the second datarepresentation between and before a first signal processing path and asecond signal processing path, after the first signal processing pathand the second signal processing path, or within the interfacecomponent.
 17. The sensor interface module of claim 11, wherein theswitching component is further configured to swap different polaritiesof the first sensor element and the second sensor element to communicatethe first data representation and the second data representation of themeasured quantity based on an asymmetrical sequence for identificationof at least two time periods corresponding to the polarities, based ondifferent durations, or based on a marker inserted into a point in aswapping sequence for swapping the polarities.
 18. A method for a sensorinterface comprising: providing a first data representation of a sensedquantity from a first sensing element; providing a second datarepresentation of the sensed quantity from a second sensing element thatis a different representation than the first data representation; andgenerating an output signal to a node based on the first datarepresentation and the second data representation.
 19. The method ofclaim 18, further comprising: switching the first data representation ofthe sensed quantity to the second data representation of the sensedquantity based on a switching sequence that is a function of at leastone of different duty cycle ranges, different times in a time domain, asame range but different time multiplexing operations.
 20. The method ofclaim 19, wherein the different duty cycle ranges or the same rangecomprises less than an entire range to facilitate communication ofstatus information within a guard band portion of the entire range. 21.The method of claim 18, further comprising: generating the first datarepresentation as a sine signal, a first inverted signal with respect tothe second data representation or an first addend of a sum; andgenerating the second data representation as a cosine signal, a secondinverted signal with respect to the first data representation, or asecond addend of the sum.
 22. The method of claim 18, furthercomprising: providing a test signal to at least one of a pull uptransistor coupled to a first signal processing path or a pull downtransistor coupled to a second signal processing path to determine anoperational status; and in response to the operational status, switchinga first signal component in the first data representation of the sensedquantity from the first signal processing path to a second signalcomponent in the second data representation of the sensed quantity fromthe second signal processing path.
 23. The method of claim 18, furthercomprising: determining a correct value or an error in the output signalbased on the first data representation and the second datarepresentation of the sensed quantity being communicated differently asa function of a difference in a duty cycle range, as a difference in arange of time, or as a function of a difference in time multiplexing.24. The method of claim 18, further comprising: comparing a modulatedsignal period of the output signal with an oscillator, wherein the firstdata representation and the second data representation are provided witha same duty cycle range and a different time multiplexing from oneanother.